Kitty Sill is the sturdiest window perch on the market. It has advanced engineering for strength, ease of assembly, and for an asthetically pleasing oval design. Includes two methods of attachment to the window sill: Velcro for easy removal from the window sill, and screws for a more permanent attachment. Supports over 40 lbs. Many indoor cats love the soft and comfortable feel of this kitty sill.